Wipro React Js Frontend Developer Interview Questions and Answers

Q1. Frontend developer
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Html, CSS, bootstrap, JavaScript, react.js

Q1. All javascript core concepts and react hooks
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Find the max values, promises, async await

Complex it is not expected hard Interview

Q1. What is jsx and es6
Ans. 
JSX is a syntax extension for JavaScript that allows HTML to be written in React components. ES6 is a newer version of JavaScript with additional features.
• JSX allows developers to write HTML-like code within JavaScript files

• ES6 introduces new syntax and features like arrow functions, classes, and template literals

• JSX is transformed into regular JavaScript by tools like Babel before being rendered in the browser
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Q2. What is arrow function
Ans. 
Arrow functions are a concise way to write functions in JavaScript.
• Arrow functions do not have their own 'this' keyword.

• Arrow functions are more concise than traditional function expressions.

• Arrow functions do not have their own 'arguments' object.

• Arrow functions are best suited for non-method functions.

• Example: const add = (a, b) => a + b;
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Q3. What is lazy loading
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Lazy loading is a technique used in web development to defer loading non-essential resources until they are needed.
• Lazy loading helps improve page load times by only loading resources when they are required.

• It is commonly used for images, videos, and other media files on websites.

• Lazy loading can be implemented using libraries like React.lazy() in React.js.
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Q4. Do you know how to code optimize
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Yes, I have experience in coding optimization to improve performance and efficiency.
• Identifying and removing unnecessary code or dependencies

• Minifying and compressing code for faster loading times

• Using efficient algorithms and data structures

• Reducing the number of API calls by batching requests

• Implementing lazy loading for resources to improve page load times
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Q5. Do you know conditional rendering
Ans. 
Conditional rendering in React allows components to render different elements or components based on certain conditions.
• Use ternary operator to conditionally render elements

• Use logical && operator for conditional rendering

• Use if-else statements inside render method for more complex conditions
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Q1. What is the mechanism of virtual DOM?
Ans. 
Virtual DOM is a lightweight copy of the actual DOM that React uses to improve performance by minimizing direct manipulation of the actual DOM.
• Virtual DOM is a representation of the actual DOM in the form of a lightweight copy.

• When changes are made to the virtual DOM, React compares it with the actual DOM to identify the minimal number of changes needed.

• This process helps in optimizing performance by reducing direct ma...read more
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Q2. What is reconciliation in react?
Ans. 
Reconciliation in React is the process of updating the DOM to match the virtual DOM.
• Reconciliation is the algorithm that React uses to update the UI efficiently.

• It compares the virtual DOM with the previous virtual DOM and only updates the necessary components.

• Reconciliation helps in improving performance by minimizing DOM manipulations.

• Key prop is important for reconciliation to identify which items have changed, adde...read more
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Q3. What are closures?
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Closures are functions that have access to variables from their outer scope even after the outer function has finished executing.
• Closures allow functions to access variables from their parent function's scope

• They maintain a reference to the variables they need, even after the parent function has finished executing

• Closures are commonly used in event handlers and callbacks
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Q4. What is hoisting?
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Hoisting is a JavaScript mechanism where variable and function declarations are moved to the top of their containing scope during compilation.
• Hoisting applies to both variable and function declarations.

• Variable declarations are hoisted to the top of their scope but not their assignments.

• Function declarations are fully hoisted, meaning they can be called before they are declared.
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Q5. What are es6 features ? and code output
Ans. 
ES6 features are modern JavaScript syntax enhancements that make code more concise and readable.
• Arrow functions for more concise syntax: const add = (a, b) => a + b;

• Let and const for block-scoped variables: let x = 5; const y = 10;

• Template literals for string interpolation: const name = 'Alice'; console.log(`Hello, ${name}!`);

• Destructuring assignment for easily extracting values from objects or arrays: const { firstNam...read more
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Q6. What is react fiber?
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React Fiber is a complete rewrite of React's core algorithm for rendering UI components.
• React Fiber is a reimplementation of the React core algorithm.

• It allows for incremental rendering, prioritizing updates based on their priority level.

• Fiber reconciles the virtual DOM tree in a more efficient and flexible way.

• It enables features like error boundaries, async rendering, and more.

• Fiber was introduced in React version 16
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Q7. How do you implement dark mode in an application?
Ans. 
Implementing dark mode in an application involves changing the color scheme to darker tones for better visibility in low light environments.
• Use CSS variables to define color schemes for light and dark modes

• Toggle between light and dark mode using a state variable in React

• Apply the appropriate color scheme based on the selected mode

• Allow users to switch between light and dark mode using a toggle button
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Q1. What is agile ? What ceremonies does your project follow?
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Q2. What are some bottlenecks you faced in your project?
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Q1. Salary discussion and basic negotiation questions
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Based on the latest react version.

Mathematics question

Q1. What is react js
Ans. 
React JS is a JavaScript library for building user interfaces.
• React JS is a front-end library developed by Facebook.

• It allows developers to create interactive user interfaces.

• React uses a component-based architecture for building reusable UI components.

• It uses a virtual DOM for efficient rendering of UI components.

• React can be used to build single-page applications, mobile apps, and more.
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Q2. What is hooks in react
Ans. 
Hooks in React are functions that let you use state and other React features without writing a class.
• Hooks were introduced in React 16.8.

• They allow you to use state and other React features in functional components.

• Some commonly used hooks are useState, useEffect, useContext, and useRef.

• Hooks help in reusing stateful logic across components.

• Example: useState hook is used to add state to a functional component.
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Q1. Tell me about your self
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What is react , feature, axios, API

Redux Redux toolkit Redux thunk